Trolley switch and frog



0t.2'7,1942. L DAVIS j 2,299,880v

TROLLEY SWITCH AND FROG yFilm1 Nov. 2e, 1940 snets-sneet'l D [3" l2 Izo- LELAND L. DAVIS l (ttorncg Oct. 27, 1942. l., DAVIS TROLLEY swITcHAND FROG Filed Nov. 26, 1940 4 Sheets-Sheet 2 :Snnentor Oct. 27, 1942. 1uAvlsf TRLLEY swITcH Aub FROG 4 sheets-Sheet 3 Film Nov. 2e, 1940 LzzmL. Davis Y l. L. DAvls 2,299,880 TnoLgE swI'rcH FROG y Enga Nov?. 26,1940 4 sheets-snee; 4

A :inventor LELANDLAvIsM I .I

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, Patented Oct. 27, 1942 UNITED STATES `PATENT OFFICE TROLLEY SWITCHANDl FROG Leland L. Davis, Kansas City, Mo.,` assigner to The Ohio BrassCompany, Mansfield, Ohio, a corporation of New Jersey ApplicationNovember 26, 1940, Serial No. 367,203

Claims.

My invention` relates to overheadA electrically operated switches whichare particularly adapted for use in an overhead system. for theoperation of the trolley bus` employingl two` current collectors.

One object of my invention is to provide an electrically operatedoverhead trolley switch to guide one or two current collectors on amoving vehicle along the main trolley wires at a branch `point in theoverhead construction or onto the branch trolley wires.

Another object of my invention is to provide a switch for use at thejunction of main and branch conductors in which the setting of theswitch for guiding the current collectors therethrough is controlled bythe direction of travel of the vehicle `upon which the currentcollectors are mounted,`at the time of passing the switch.

Another object of my invention is to provide an overhead electricallyoperated trolley switch provided with a pair of shunt coils to operate ithe tongues of the switch to either of its two positions and includingmeans to interrupt the flow of current to the coils after operating theswitch to prevent overheating and damage to the coils.

A further object of my invention is to provide an velectrically operatedtrolley switch arranged with tongues to guide the current collectors ona moving vehicle, with means to open the circuits to the electricallyoperatedH mechanism for positioning the switch tongues to preventoverheating the mechanism and also to provide means to prevent or`red'ice the arc which would otherwise form upon opening the circuitsand thereby` destroy the contacts.

A further object of my invention is to provide an electrically operatedoverhead trolley switch in which theelectrically operated mechanism forpositioning the tongues is provided with protecting means, the saidmeans comprising auxiliary switching means to interrupt the ilow ofcurrent to the operating mechanism to prevent damage tothe mechanismfrom overheating and including a condenser to prevent or reduce the arcwhich would otherwise form at the opening of the-switch. f i

A still further object of my invention is to provide means to dischargethe condenser after absorbing the energy produced by interrupting thecurrent flow tok the electrically operated mechanism.

Another object of my invention is to provide anoverhead electricallyoperated switch provided with tongues to guide the lcurrent collectorson a moving vehicle and a plurality of operating coils therefor, with asingle auxiliary switch to interrupt the flow of current to theoperating coils in order to protect the operating coils from overheatingand to provide a single condenser to eliminate or greatly reduce thearcing` at the auxiliary switch to prevent damage to the contacts at thepoints of break.

Another object of my invention is to provide a switch having twoelectrically operated frogs for use on an overhead .system employing twotrolley wires of opposite polarity whereby the current collectors on amoving vehicle are guided through the switch in predetermined paths andin `which is employed a single mechanically operated auxiliary switch tocontrol the energization of the operating mechanism of both frogs andmeans associated with the frogs to` insure operation of both frogsbefore the auxiliary switch effects the deenergization of theelectrically operated mechanism.

Another object of my invention is. to provide the aforementionedcondenser with means to limit the discharge current thereof to preventburning and pitting oi the contacts of the auxiliary switch upon closingthe same.

Other objects and advantages will appear as the description of theparticular physical embodiments selected to illustrate the inventionprogresses,` and the novel features will be particularly pointed out inthe appended claims.

My inventions herein disclosed relate to new and novel constructions,combinations, and relations of the parts described inthis specificationand shown in the drawings forming a part thereof.

In the drawings: Y

Fig. 1 shows a schematic arrangement of one form of my inventionemploying shunt operating coils as applied to trolley bus operation fora left-hand turn-.out in which the movement of the frog tongues iscontrolled by the direction of travel of the vehicle relative to themain trolley wires and shows the relation of the parts after a bus haspassed straight through the switch.

Fig. 2 shows schematically the same switch as in Fig. 1 but shows therelation of the parts after a bus has passed through the switch and ontothe branch wires.

Fig. 3 shows a top view of a single frog arranged for a right-handturn-out with the cover partly removed to show the tongue operatingmechanism and aforementioned auxiliary switch.

Fig. 4 is a side view of Fig. 3.

Fig. 5 is an end view of Fig. 3.

Fig. 6 is a section on the line 6 3 of Fig. 3.

Fig. 7 is a side view in partial section of the auxiliary switchreferred to hereinabove.

Fig. 8 is a top View of Fig. 7

Fig. 9 is an end View of Fig. '7.

Fig. 10 is another end View opposite to Fig. 9 in partial section of theauxiliary switch, showing one relation of the parts to the operatinglever when the frog tongue is. midway between its two guiding positions.

Fig. 11 is an end View in partial section corresponding to the end viewof Fig. 10, but showing the relation of the parts to the operating.lever when the frog tongue is in one of its two guiding positions.

Fig. 12 is a partial section on the line IEM- i2 of Fig. 10.

Fig. 13 is a schematic arrangement of a modined form of my inventionemploying shunt and series operating coils and showing the relation ofparts after a bus has passed straight through the switch.

Fig. 14 is a schematic arrangement of my invention shown in Fig. 13 butshowing the relation of parts after a bus has passed through the switchalong the turn-out.

Electrically operated switches for use in overhead trolley systems foroperating trolley buses the resistance of each coil will besubstantially one-half that of coils constructed to be connected inparallel across the trolley wires.

The plungers 1 and 'I' are preferably slidably positioned in a brass orcopper tubing I-I 0 respectively and the tube I0 is slottedlongitudinally at I I as later explained.

The description above is directed particularly to the frog F but thefrog F is equipped in like manner and the parts described function asthose of frog F.

My invention is installed at the junction of the branch trolley wirewith the main trolley wire. To control the operation of the switch, Iinstall in the trolley wire 4 a contact A and in the trolley wire 4', apair of longitudinally arranged contacts B and C. The contacts A and Bare 'so positioned longitudinally relative to each other on the approachside of the switch that the contacts will both be in engagement with thecurrent collectors 6 and 6 as the trolley bus turns to take the turn-outas shown schematically in Fig. 1 by the dotted line and arrow'X, but thecontacts A and B will not be in engagement with the current collectors 6and 6 at the same time if the bus operator intends the bus4 to passstraight through the frogs along the main wires as indicated by thedotted lines and employing two current collectors are now in use butsuch switches lack certain refinements and improvements which arerequired to make them more practical and to meet ever increasingadvancements.

My inventions are shown schematically in Figs.

In the preferred embodiment of my invention, i

I provide a switch comprising a pair of trolley frogs F-F held in spacedrelation by insulators I. The frogs are provided with a pan 2 2' andmovable tongues 3-3 respectively. The tongues are pivotally mounted andmovable to either of two positions, one as shown in Fig. 1 which is thestraight through position and the other as shown in Fig.- 2 which is theturn-out position.

To the frog F is secured the main trolley wire i and the branch wire 5;to the frog F is secured r the main trolley wire t and the branch wire5.

The tongues 3 3 guide the current collectors 6 6 along the main wires orfrom main to branch trolley wires as required.

Frog F is provided with two coils and a plunger for operating the tongueto either of its positions depending upon which of the coils isenergized. These coils in the arrangement shown in Figs. 1 and 2 areshunt coils, that is, they are wound to be connected between the maintrolley wires without the addition of resistance. shown, the coil Swhich is mounted on the pan 2, when energized, will move the plunger ormagnetic core 'I to the left and through the medium of mechanism shownin Figs. 3 and 4 and later described the tongue 3 which is pivoted tothe pan 2 at 9, will be moved to the straight through position as shownin Fig. 1.

When the coil T is energized the plunger '.I will be moved to the rightand the tongue 3 moved to the turn-out position as shown in Fig. 2.

The coils S-S of the frogs F-F respectively are connected in paralleland the same is true of the coils T and T. The coils S-S of the twofrogs and the coils T and T of the two frogs may be connected in series,if desired, in which case arrow Y.

Further, the contacts A and C are so placed longitudinally relative toeach other that they will both be in engagement with the currentcollectors 5 6 when the bus operator intends to go straight through theswitch but not so if he intends to take the turn-out.

Each contact is so constructed and arranged relative to its trolley wirethat it will be energized while the current collector is in engagementtherewith as the current collector will have simultaneous engagementwith the trolley wire.

The contact A is connected to *bothl coils on both frogs since it playsa part in the operation of the switch when the bus passes straightthrough the switch or takes the turn-out.

To effect proper energization of the coils on both frogs, the contactsA, B and C are connected thereto as follows: The conductor I2 connectsthe contact A with the auxiliary or circuit control switch D (laterdescribed).

The switch D is connected with the coils S and S' by the conductor I3and with the coils T and T by the conductor It. The coils S and S areconnected with the contact C bythe conductor I5 and the coils T and Tare connected with the contact B by the conductor I6.

The auxiliary switch D in general comprises two sets of contacts eachset constituting what might be termed sub-switches d and d respectivelyfor controlling the circuits to the coils. When the contacts of d areopened, the contacts of d are closed and vice versa (see Figs. 1 and 2),and one purpose of the switch D is to open the circuit to the energizedcoils on the two frogs after the tongues have been properly positionedto prevent overheating and damage to the coils should the currentcollectors come to rest while in engagement with the contacts A, B and Cand simultaneously close the circuit to the other pair of coils andplace them in condition to be energized later.

The auxiliary switch D may be operated directly by the plunger 1, but Iprefer to use the lever arm I'I' which is secured to the tongue at 9and, therefore, moves with the tongue.

` lever I1by`the insulating knob I9.

` 2| `and the blade 20 makes and breaks contact with the xed contact 2 IItwill be noted that the insulating member I9 is of less 1lengthv than`the space between the blades 20 and 20', "therefore, when the tongue 3is inits intermediate position betweenits extreme guiding positions, theblades 20 and 20"'fwill each be in engagement with its contactZI or12Ilrespectively,hthus connecting the contacts12I and l 2 I "momentarilywhile the tongue moves between l its `extreme positions since the blades2U and 20 are connectedn at one end.

The purposeof providing a momentary connection of xed contacts 2I and 2|is toaid in' the useuof a condenser across the `breaks when thecontactsof d and d open the circuit. Iliave found that a condenser across thecontacts at d and d will prevent or reduce the arcingatthe opening ofthe contacts andthis is very advisable, because such arcing would `veryshortly destroy the contacts since thelsystem employs as a rule 600volts betweentrolley wiresand any flash would linger for a considerabletime.

I find with the arrangement of the circuits as lshown,` one switch D Aissuflicient to control all coils on both frogs and that `with the switchD as constructed` asingle condenser 22 will control l the arcingat bothsets of contacts at d and d' asA the short-circuiting of the contactsmomentarily will dissipate or discharge the charge taken up by thecondenser at the separation of the contacts under load.

When the lever II is moving between itslimits, there is during a periodof time during the travel of the lever when theV both sets of contactsat d and d" will be closed at the' sameV time, thus short-circuiting thecondenser through the resistance 23. The resistance 23 limits the rateof discharge of the condenser and prevents burning of the contacts ofthe sub-:switches d and d which would otherwise take place if the fulldischarge `of the condenser were permitted at d or d just prior to Vtheclosing of the contacts thereof.

`The resistance 23 is relatively small and, therefore, it has little`effect upon the rate of charge of `the condenser 22 or upon itsabsorption of `a charge but it is of sufficient resistance toeffectively limit the discharge current from the condenser to a valueconsistent withv the current carrying ability ,of the contacts.

Since the condenser is shorted at each operation of the tongue and ofthe switch D, it is only necessary to use one condenser and oneresistance toprotect the coils of both frogs F and F.

I prefer to associate the switch D with 'that contact device (ContactA)and with' that trolley wire (shown as negative) common to all coils. Thecondenser 22 absorbs the energy released by the` magnetic field upon`interruption of the current atd and d. z f

The tongues-of fthe two `frogs are not mechanically connected;therefore, both tongues are not compelled to move simultaneously. l Ifythe operating mechanism of the frog lF should response rst and shouldvoperate the switch D beforethe mech- .anism of the frog F hasoperatedthe tongue on frog -F, .Athen theffrogA tongues .would `be set.; at

circuit through the coilsA S and S will be opened To overcome `thiscondition, the metalll tubing I0 of the frog Ff, maybe slotted from endto end thus the generationioflinduced current inthe tube, whichwouldotherwise :oppose the mag.- netising effect of the coils S` and T',`would .be prevented; the unsplit tube Il) of the frogF will act toretard the magnetising effect ofv the coils S andT due lito the inducedcurrents set upin vthe tube andthe heavierfthe. `tubing Athefggreateristhe retarding effect. Hence the tonguebffrog F would respond toenergization ofthe coils C' and Tbefore the switch D is operated.

Further, the response of the mechanism on the 4 through contact B,through conductor I6, coils T and T', conductor I4, contacts d',conductor I2, contact A` to trolley 4thus energizing coils T and T andoperating the tongues 3-3' to their turn-out-positions. As the busproceeds :thecollector 6 `will engage the contact C, but the coils S andS will not beenergizedfbecause the circuit th-rough the coilsS and Swill'beopened at the contactA.

Assuming the switch.` set` as in Fig. 1 :and `the 'bus operator `desiresto go straight through as shown by Y; the `currentcollector 6'willenergize the contact TB fromv the vtrolley wire 4 but thecoils TandT" will :not be energized because `the circuitwill be opened at` A.As the bus proceeds, the current collectors 6 and I5.v will energize thecontactslA and C respectively, but the at contacts cl` and the circuitthrough` the coils T and T will be openedi at contact B.

Assuming thesetting `of the switchas in Fig, 2, and the bus operatordesires to go straight through asshown by Y; when the current collector:E engages and energizes the contact B,

the `coilsT and T `will not be energized because the circuit`therethrough will be opened at, d', but as the bus proceeds andcollectors Band 6 will energize contacts A` andC respectively and thecircuit through the coils Sand S will be completed by way of conductorsI5 and I3, subswitch d, and conductor I2.

. Assuming the setting as inFig. 2 and the bus operator wishesfto-maketheturn-as shown by `X; the collectors Band 6-wil1 energize thecontactsAland B respectively, but the circuit through the coils T and Twill be openedat sub-switch vd ord'opened `under load, but the:condenser 22rwi1lwabsorb. theenergy [either ,whollyorin 75.

part. depending upon itsfcapacity,` and if Vthe bus r variance .toguide. the currentslcollectons ,.to; dif- 1 ferent positions.

Vend plate 3| by the screws 33.

should stop with the current collectors on the contacts the opening ofthe proper set of contacts at d or d will prevent overheating the coils.

In the foregoing description, I have described the various essentialelements of my invention and the function and operation of the switch asa part ofthe overhead system with respect to a moving bus. I will nowdescribe the specific form. of auxiliary or circuit control switch Dwhich I use, although other forms or modifications may be used whichwill come within the scope of my invention as later claimed.

The speciiic construction of the operating mechanism is shown in Figs. 3to l2 inclusive. Mounted upon the pan 2 is a frame 3Q supporting thecoils S and 'I'. A yoke 32 is secured to the The pintle 34 is secured toand pivots with the tongue 3 and pro-- jects above the upper surface ofthe pan E. Secured to the pintle or stem 3d is a lever 35 (il in Figs. 1and 2). Pivotally mounted on the yoke 32 is a latch 36 under tension ofthe adjustable spring 3l. The proje-cting end of the magnetic core l isattached to the lever 35 intermediate its ends whereby the lever ismoved about the axis ci the pintle 3E as the core 'i is moved in eitherdi rection depending upon which coil is energized. The free end of thelever 35 engages a roller on the latch 36 whereby the lever isreleasably held in either of its two positions. The cover 38 protectsthe mechanism mounted on the pan from the weather.

kMounted on the support d is a second support 43 provided with a slot tewhich permits lateral adjustment along the longitudinal axis of thecoils relative to the lever 35. The switch D is held in adjustedposition by the screw 42.

Depending from the member i3 is the member 45 of insulating material andheld thereto by screws 45. On opposite sides of the member d5 are clampsdl, preferably of insulating material but which may be of metal, andeach is provided with a groove to receive the insulated conductors f 48and-49 (conductors I3 and lli of Fig. 1) and the screw-bolts 5t hold theparts in position.

The member i5 is provided with dovetailed grooves 5i, one on each sideface thereof and in each groove there is positioned a copper plate52-52' respectively (2i and 2i' of Fig. 1) and to which the conductorsi8 and t@ are connected respectively.

Positioned between the members d3 and the block 45 but insulated fromthe member 43 by insulation 53, is a U-shaped conducting member havingdepending blades 5&-54 (2i) and 2li of Fig. 1) of phosphor bronze orresilient copper and connected at one end by a square bend. The bladesare provided with contact'studs 55-55 to engage the plates 52.-52.

When the switch D is in position as shown in Figs. 3 and 4, the lever 35is positioned between the blades SLi-5t and insulated therefrom byinsulation 56, and the lever 35 as it moves in either direction engagesthe blades to move them to their open position. The insulation 56 may beattached to the blades. In Fig. 10 the lever 35 is shown in mid-positionas when the tongue is in Cil mid-position between its extreme or guidingpo- 75 sitions. In Fig. 11 the lever is shown as engaging blade 511' andhaving broken contact between the blade 5t and the plate 52.

In Figs. 13 and 14, I show schematically a modied -form of my inventionin which the switch is operated by what I designate as a power-on and apower-oi method. In this arrangement, I employ shunt coils S and Srespectively for the frogs I-I and H and, also, series coils R and Rrespectively. The shunt coils automatically position the tongues toeither one of their positions as may be predetermined as in the case ofthe S-S' coils in Fig. l, and the series coils position the tongues tothe other position but require the bus operator to move his controllerto one of its on positions in order to effect the energization of thecoils Rf-R which is not the case with the coils T T of Fig. l. I make noclaim to the power-on and power-off idea as the same has been in use forquite some time, but even a switch so operated is very likely to haveits shunt coils overheated if subjected to current for too long a time.

I have indicated with like characters certain parts of Figs. 13 and 14which are common with the disclosure in Figs. l and 2 where the partsare the same or function the same. The frog pans 2 2 are held in spacedrelation by insulato-rs i and each frog is provided with a tongue 3 3respectively. Associated with the trolley wire Il is a shunt contact 'I0and a series contact il. The contact ll is connected to the coils S-S,which are connected in parallel, by the conductor 12, rIhe contact 'I'iis connected to the series coils IiP-R', which are connected in series,by the conductor 73. The circuit to the series coils is completed by theconductor 'M which connects the coils to the trolley wire 4 or pan 2'.

The series coils are of much heavier wire than the shunt coils sincethey must withstand a very happy flow of current when the contact TI isengaged by the current collector 6 with the controller set to power-onbut the time of such ilow is only while the collector moves across thecontact as the current ilowing through the coils R-R also flows throughthe motors of the vehicle, hence the current collector 6 does not engagethe contact 7i with power-on for any great length of time as the buswill keep moving.

Since there is little danger of the coils R-R being overheated, Iprovide no means to protect them but the shunt coils S-S' are subject tooverheating if the bus stops with the collector 6 on the contact itlwhich is energized at such times; therefore, I provide an auxiliary orcircuit control switch E to open as soon as the coils S-S have operatedto move the tongues to the straight through position as in Fig. 13. Thelever il', which moves with the tongue 3, operates the switch E whichcomprises the blade 'l5 and xed contact I6.

The coils S-S are connected to the switch E by the conductor Il and thecircuit is completed by the conductor 73 which connects the switch bladei5 to the pan 2 which is of the same pclarity as the trolley wire A;therefore, the knob i9 on the lever il which engages with the blade 75is not insulated as the blade 'l5 of the switch E is of the samepolarity as the pan 2 at all times.

Assulming the parts of the switch are in the relation shown in Fig. 13then the switch functions as follows when `a bus passes the contacts; asthe current collector E engages the contact l0 the same is automaticallyenergized but the coils -'S :will not be energized as the circuit isopen at E; if the bus operator wishes to go straight through, he thenpasses the contact 1l with power-off?? and in that case no current vwillflow through the coils Rf-R to energize them suiciently to operate theswitch; if, however, the operator wishes to take the turn-out he throwshis controller ,to power-on and the current flows from the -charged pan2', through the conductor 14, coils R-R, conductor 13, contact 1lthrough the motors and current collectors of the bus to the trolley wire4, thus properly energizing the coils R-R' and moving the tongues to theturnout position as shown in Fig. 14.

Assuming the switch is in the condition shown in Fig. 14, then theswitch functions as follows when a bus passes the contacts; when thecurrent collector engages the contact it is energized and current willflow through the conductor 12, coil-s S-SQ conductor 11, switch E,conductor 18, to the pan 2, thus automatically energizing the coils S--Svand setting the tongues 3 3 to the straight through position. If thebus operator wishes to go straight through he turns his controller topower-off, but if he wishes to take the turn he applies power-on andwhen the collector 6 engages the contact 1l, current will flow throughthe conductor 14, coils R-R, conductor 13, contact 1 I, through the busmotors and current collectors to the trolley wire 4, thus energizingthecoils R-R' and returning the tongues to the turn-out position.

In order to protect the contact and blade of the switch E from burningdue to arcing when the switch opens under load, I connect a Icondenser22 across the break to albsorb the energy of the are, and to limit therate of discharge of the condenser when the contacts approach inclosing, I introduce a resistance 23 in series with the condenser. Anycharge in the condenser will be dissipated'when the contacts of theswitch E engage and the condenser will beready to absorb the energy ofthe arc when the -contacts separate and thus prevent or reduce thedestructive effects of the arc upon the contacts.

Having described my invention, I claim:

1. In an overhead trolley switch employing a pair of trolley frogs 'eachprovided with a movable tongue adapted to guide -a current collectoralong a main lconductor or on to a branch conductor at a turn-out andelectrically operated mechanism for ea-ch frog including a pair of coilsto operate each tongue in opposite directions, the combination therewithof means to control the 4energization of the coils of said mechanismsinif clu'ding means associa-ted with one frog and operated bytheme'chanislm thereof to alternate the energization of the coils oneach frog and also including means to retard the operation of themechanism associated .with said one frog with respect to the operationof the other mechanism.

2. In a trolley switching system for a pair of current collectors on atrolley bus, in combination, a pair of main trolley wires, a branch wirefrom each main wire, a trolley frog at each junction of each main andbranch wire, each frog having a movable tongue to guide the collectorsalong the main wires or on to the branch wires, electrically operatedmechanism for each frog, ,each mechanism including a pair of unconnectedand opposed coils associated with each frog to operate the tonguethereof to either of its two positions, one coil of each frog connectedto the respective or corresponding coil of the other frog whereby eachpaifr of connected -coils will be separately energized, a circuitcontrol means associated with one frog and connected to the coils ofboth Ifrogs and operated by the mechanism of said one frog to effect thealternate energization of the coils of ea-ch frog and move the tongueson both frogs to corresponding positions, contact devices associatedwith the trolley the circuit control means being so connected that thesaid -coils on both frogs will be so selectively energized as to movethe tongue on each frog to one or the other of its positions dependingupon the energization of the contact devices, and l means associatedwith each frog to control the rate of energization of the coils of onefrog relative to the rate of -energization of the coils of the otherfrog whereby the operation of the mecha-` nism 'with said one frog will'be retarded with respect to the operation of the mechanism of the otherfrog.

3. A trolley switch for a trolley system employing a pair of mainconductors of opposite polarity and a branch wire for each main wire andarranged to gui-de a pair of current collectors mounted on a vehicle,comprising in combination, a trolley frog at the intersection of eachmain and branch conductor, each frog provided with a. movable tongueforming a guide for the current collectors, electrically operatedmechanism for each tongue to operate the tongue to either of itspositions, each mechanism provided with a pair of unconnected opposedoperating coils to actuate the mechanism in opposite directions, onecoil of eachfrog connected to the corresponding coil of the other frogwhereby the connected coils will 'be energized and de-energizedsimultaneously, means actuated by a member of the electricallyoperated'm'echanism on one frog toV effect alternate energization of theconnected coils, and lmeans to retard the rate of operation of theelectrically operated mechanism associated with the said one frog withrespect to the operation of the mechanism of the other frog.

4. A trolley switch for a trolley system employ-` ing two trolleyconductors of opposite polarity and la branch wire from ea-ch trolleywre,the switch having two mechanically connected but insulated frogseach having a movable tongue to guide a pair of current collectorsmounted on a vehicle, and each frog provided with electrically operatedmechanism to move the tongue thereon to either of two positions, thecombination with the electrically operated mechanism of one frog ofmeans operated by the lastsaid mechanism, the said means beingelectrically connected to each mechanism whereby selective energization.of ea-ch -mechanism is effected to operate the tongues to either of tworespective positions, the said means being arranged to effect alternateenergization of the mechanism on each frog to move the tongue thereof toeither one or the other of its positions, and means'associated with andcooperating with the aforesaid one frog to retard the operation of themechanism thereon with respect to the operation of the mechanism on theother frog.

5. In an overhead trolley switch, in combina'- tion, a pair ofelectrically operated trolley frogs, each frog adapted to guide acurrent collector 5 along a main wire `or on to a branch wire at aturn-out, ope-rating mechanism on each frog and Which includes a pair ofopposed coils, the correspondingly operating -coils of the two frogsbeing connected for simultaneous energization and to eiect actuation ofeach frog to either of 4its two positions, means actuated by theoperating mechanism of one frog to effect alternate energization of the`connected coils of each frog and means to control the relative rate ofenergization of thecoils 'whereby the operation of the operatingmechanism associated with the said one frog will 'be retarded Wi-threspect to the movement of the operating mechanism on the other frog.

LELAND L. DAVIS.

